Insulated copper based cable is commonly used for automotive wiring. Copper has high conductivity, good corrosion resistance and adequate mechanical strength. However, copper and copper based alloys are relatively expensive and are also heavy.
Interest in weight savings and cost savings in automotive electrical wiring applications have made aluminum based cables an attractive alternative to copper based cables. However, some wiring and electrical connectors may remain copper based. Thus, there may be a transition somewhere in the electrical circuit between an aluminum based portion of the circuit and a copper based portion of the circuit. Often this transition may occur at the terminal because the terminal may remain copper based for reasons of size and complexity of shape that can be more easily achieved with copper based materials over aluminum based materials. The crimp interface connection of aluminum based cable to a copper based terminal can produce a galvanic corrosion of the aluminum at the interface, if an electrolyte, for example salt water, is present. The galvanic reaction corrodes the aluminum because the aluminum or aluminum alloy has a different galvanic potential than the copper or copper alloys of the terminals. “Copper based” as used in this document means pure copper, or a copper alloy where copper is the main metal in the alloy. Similarly, “aluminum based” as used in this document means pure aluminum or an aluminum alloy where aluminum is a main metal in the alloy.
It has long been known to apply grease to cover the interface between a cable and a terminal. However, grease has been shown to be an ineffective preventative in the long term under harsh automotive environments where salt sprays and water pressures can easily wear away at the grease and expose the crimp interface. In the case of an aluminum and copper interface, even a small amount of exposed aluminum cable can contribute to significant galvanic corrosion.
What is needed is a connection between aluminum based cable and copper based terminals with improved corrosion resistance through an improved seal to seal the aluminum cable from an electrolyte. What is also needed is a durable and complete seal about a terminal connection for reducing galvanic induced corrosion.